Aim: To evaluate the flexural strength and surface hardness of chemically activated provisional polymethyl methacrylate (PMMA) resin incorporated with 2.5% zirconia, titanium, and aluminum oxide (Al2O3) nanoparticles after 24 hours in distilled water and 2 weeks in artificial saliva after fabrication.
Materials and methods: According to International Organization for Standardization (ISO) 10477:2018, a rectangular-shaped die with 25 mm l × 2 mm w × 2 mm h and wheel shape die with a diameter of 15 mm and thickness of 1 mm were made to investigate the flexural strength and surface hardness. A total of 160 samples were prepared and categorized as groups F (flexural strength) and S (surface hardness). Groups F and S were further subdivided into two groups—group I (24 hours in distilled water) and group II (2 weeks in artificial saliva), then they were subdivided into group A (control) no nanoparticle, group II (2.5% zirconia), group III (2.5%titanium oxide), and group IV (2.5% Al2O3). A total of 10 samples were fabricated in each category the flexural strength test was done using a universal testing machine and the hardness test was done using a digital Vickers microhardness tester. The obtained values were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) test at a significant level of p < 0.05.
Results: The mean values of flexural strength of autopolymerized provisional PMMA resin control, zirconium dioxide (ZrO2), titanium dioxide (TiO2), and Al2O3 nanoparticles reinforced groups in 24 hours in distilled water were 97.96, 152.81, 140.79, and 137.85 MPa, respectively, and 2 weeks in artificial saliva were 98.43, 150.43, 141.06, and 139.00 MPa, respectively. The surface hardness of autopolymerized provisional PMMA resin control, ZrO2, TiO2, and Al2O3 nanoparticles reinforced groups in 24 hours in distilled water was 28, 33.9, 32, and 30.8 Vickers hardness test (VHN), respectively, and 2 weeks in artificial saliva were 28.7, 34, 32, and 32 VHN, respectively.
Conclusion: Autopolymerized provisional PMMA resin reinforced with 2.5% zirconium nanoparticles showed statistically significant flexural strength and surface hardness than conventional provisional PMMA resin and 2.5% TiO2 and 2.5% Al2O3 nanoparticles reinforced groups after 24 hours in distilled water and 2 weeks in artificial saliva after fabrication.
Clinical significance: The provisional restorations are subjected to masticatory forces during function and are easily prone to fracture. The use of autopolymerized provisional PMMA resin reinforced with 2.5% zirconium nanoparticles increased the mechanical properties of the provisional restoration; hence, it can be recommended for provisional restorations to increase the life span in clinical practice.